This invention relates to nuclear reactors and it has particular relationship to the replacement of damaged old split-pin assemblies (OSPA's) by new split-pin assemblies (NSPA's). Split-pin assemblies are secured to the lower guide tubes (LGT's) of a nuclear reactor. The bifurcated ends, i.e., the tines, of each split pin engage in holes in the upper core support plate supporting the associated guide tube.
The guide tubes to which the OSPA's are secured typically include a lower section or lower guide tube (LGT) and an upper section or upper guide tube. The LGT and the upper guide tube are secured together coaxially by abutting flanges which are bolted together. In some guide tubes the LGT includes a lower flanged section and an upper flanged section joined axially by bolts through the flanges. The LGT has a lowermost flange having counterbores spaced circumferentially by 180.degree. in which OSPA's are secured.
Application Ser. No. 617,857 filed June 6, 1984 to Calfo et al. for Replacement of Split Pins in Guide Tubes assigned to Westinghouse Electric Corporation and the related applications referred to in Calfo et al. disclose an automatic system including robotic tooling for replacing OSPA's by NSPA's. This process has proven highly useful in situations where the split pins on all guide tubes (typically 37 to 61) of a reactor are to be replaced. Typically, the automatic system is conveyed to the site of the replacement by seven trailers and several weeks are consumed in a replacement.
The damage to an OSPA is typically a crack in the old pin. Sonic apparatus is available to determine if there is a crack in an OSPA so that replacement by an NSPA is required. Typically the use of this apparatus uncovered cracks in the OSPA's of some of the guide tubes; the OSPA's in the other guide tubes were crack free. In such cases, it is only necessary to replace the defective OSPA's and the complexity, time consumed and cost involved in the use of the automatic system outweighs its benefits.
It is an object of this invention to provide a method and apparatus (tooling) less complicated and costly than the above-described automatic system for replacing OSPA's by NSPA's, particularly when a limited number of guide tubes are to be processed but also having more general use in situations where all split-pin assemblies are to be replaced.